G.1 Introduction

In order to ensure
that SVG-family documents are maximally portable among
SVG-family user agents, this specification rigidly defines
conformance requirements for both, as well as for SVG-family
document types. While the conformance definitions can be found
in this appendix, they necessarily reference normative text
within this document and within other related specifications.
It is only possible to fully comprehend the conformance
requirements of SVG through a complete reading of all normative
references.

if all non-SVG namespace elements and attributes and all
xmlns attributes which refer
to non-SVG namespaces other than the XLink namespace are
removed from the given document, and if an appropriate XML
declaration (i.e., <?xml...?>) is included
at the top of the document, and if an appropriate document
type declaration (i.e., <!DOCTYPE svg ...
>) which points to the SVG DTD is included
immediately thereafter, the result is a valid
XML document.

The SVG language or these conformance criteria provide no
designated size limits on any aspect of SVG content. There are
no maximum values on the number of elements, the amount of
character data, or the number of characters in attribute
values.

G.3 Conforming SVG Stand-Alone Files

G.4 Conforming SVG Included Document Fragments

SVG document fragments can be included within parent XML
documents using the XML namespace facilities described in Namespaces in
XML.

An SVG document fragment that is included within a parent
XML document is a Conforming Included SVG Document
Fragment if the SVG document fragment, when taken out of
the parent XML document, conforms to the SVG Document Type Definitions (DTD).

In particular, note that individual elements from the SVG
namespace cannot be used by themselves. Thus, the SVG
part of the following document is not conforming:

G.5 Conforming SVG Generators

does not create non-conforming SVG document fragments of
any of the above types.

Additionally, an authoring tool which is a Conforming SVG
Generator conforms to all of the Priority 1 accessibility
guidelines from the document "Authoring Tool Accessibility
Guidelines 1.0" [ATAG] that are relevant
to generators of SVG content. (Priorities 2 and 3 are
encouraged but not required for conformance.)

SVG generators are encouraged to follow W3C developments in the
area of internationalization. Of particular interest is the
W3C Character Model and the concept of Webwide
Early Uniform Normalization, which promises to enhance the
interchangability of Unicode character data across users and
applications. Future versions of the SVG specification are
likely to require support of the W3C Character Model
in Conforming SVG Generators.

G.6 Conforming SVG Interpreters

An SVG interpreter is a program which can parse and process
SVG document fragments. Examples of SVG interpreters are
server-side transcoding tools (e.g., a tool which converts SVG
content into modified SVG content) or analysis tools (e.g., a
tool which extracts the text content from SVG content). An SVG viewer also
satisfies the requirements of an SVG interpreter in that it can
parse and process SVG document fragments, where processing
consists of rendering the SVG content to the target medium.

In a Conforming SVG Interpreter, the XML parser
must be able to parse and process all XML constructs defined
within [XML10] and
[XML-NS].

There are two sub-categories of Conforming SVG
Interpreters:

Conforming Static SVG Interpreters must be able
to parse and process the static language features of SVG that
correspond to the feature string "http://www.w3.org/TR/SVG11/feature#SVG-static" (see Feature strings).

In addition to the requirements for the static category,
Conforming Dynamic SVG Interpreters must be able to
parse and process the language features of SVG that
correspond to the feature string "http://www.w3.org/TR/SVG11/feature#SVG-dynamic" (see
Feature strings) and
which support all of the required features in the SVG DOM described in this
specification.

A Conforming SVG Interpreter must parse any SVG document
correctly. It is not required to interpret the semantics of all
features correctly.

Note: A transcoder from SVG into another graphics
representation, such as an SVG-to-raster transcoder, represents
a viewer, and thus viewer conformance criteria apply. (See Conforming SVG
Viewers.)

G.7 Conforming SVG Viewers

An SVG viewer is a program which can parse and process an
SVG document fragment and render the contents of the document
onto some sort of output medium such as a display or printer;
thus, an SVG Viewer is also an SVG
Interpreter.

There are two sub-categories of Conforming SVG
Viewers:

Conforming Static SVG Viewers support the static
language features of SVG that correspond to the feature
string "http://www.w3.org/TR/SVG11/feature#SVG-static" (see Feature strings). This
category often corresponds to platforms and environments
which only render static documents, such as printers.

Conforming Dynamic SVG Viewers support the
language features of SVG that correspond to the feature
string "http://www.w3.org/TR/SVG11/feature#SVG-dynamic" (see Feature strings). This
category often applies to platforms and environments such as
common Web browsers which support user interaction and
dynamic document content (i.e., documents whose content can
change over time). (User interaction includes support for
hyperlinking, events [e.g., mouse clicks], text selection,
zooming and panning [see Interactivity]. Dynamic document
content can be achieved via declarative animation or by scripts
modifying the SVG DOM.)

In environments that have appropriate user interaction
facilities, the viewer must support the ability to activate
hyperlinks.

If printing devices are supported, SVG content must be
printable at printer resolutions with the same graphics
features available as required for display (e.g., the
specified colors must be rendered on color printers).

On systems where this information is available, the
parent environment must provide the viewer with information
about physical device resolution. In situations where this
information is impossible to determine, the parent
environment shall pass a reasonable value for device
resolution which tends to approximate most common target
devices.

Resampling of image data must be consistent with the
specification of property 'image-rendering'.

The viewer must support alpha channel blending of the
image of the SVG content onto the target canvas.

SVG implementations which support the HTTP protocol must
correctly support gzip-encoded
SVG data streams according to the HTTP 1.1 specification [RFC2616];
thus, the client must specify "Accept-Encoding: gzip" [
HTTP-ACCEPT-ENCODING] on its request-header field and
then decompress any gzip-encoded
data streams that are downloaded from the server. If the
implementation supports progressive rendering, the
implementation should also support progressive rendering of
compressed data streams.

The viewer must support base64 encoded content using the
"data:" protocol [RFC2397]
wherever URI
referencing of whole documents (such as raster images,
SVG documents, fonts and color profiles) is permitted within
SVG content. (Note: fragments of SVG content which do not
constitute an entire SVG document are not available using the
"data:" protocol.)

The viewer must support the following W3C Recommendations
with regard to SVG content:

complete support for inclusion of non-SVG namespaces
within SVG content as defined in "Namespaces in XML" [XML-NS].
(Note that data from non-SVG namespaces are included in
the DOM but are otherwise ignored.)

All visual rendering must be accurate to within one
device pixel (px unit) to the mathematically correct result
at the initial 1:1 zoom ratio. It is suggested that viewers
attempt to keep a high degree of accuracy when zooming.

On systems which support accurate sRGB [SRGB] color, all
sRGB color computations and all resulting color values must
be accurate to within one sRGB color component value, where
sRGB color component values range from 0 to 255.

Although anti-aliasing support is not a strict requirement
for a Conforming SVG Viewer, it is highly recommended for
display devices. Lack of anti-aliasing support will generally
result in poor results on display devices.

Specific criteria that apply to only Conforming Dynamic
SVG Viewers:

In Web browser environments, the viewer must have the
ability to search and select text strings within SVG
content.

If display devices are supported, the viewer must have
the ability to select and copy text from SVG content to the
system clipboard.

The Web Accessibility Initiative [WAI] is defining "User Agent
Accessibility Guidelines 1.0" [UAAG]. Viewers are
encouraged to conform to the Priority 1 accessibility
guidelines defined in this document, and preferably also
Priorities 2 and 3. Once the guidelines are completed, a future
version of this specification is likely to require conformance
to the Priority 1 guidelines in Conforming SVG Viewers.

A higher order concept is that of a Conforming
High-Quality SVG Viewer, with sub-categories
Conforming High-Quality Static SVG Viewer and
Conforming High-Quality Dynamic SVG Viewer.

Both a Conforming High-Quality Static SVG Viewer
and a Conforming High-Quality Dynamic SVG Viewer must
support the following additional features:

Professional-quality results with good processing and
rendering performance and smooth, flicker-free
animations.

On low-resolution devices such as display devices at
150dpi or less, support for smooth edges on lines, curves and
text. (Smoothing is often accomplished using anti-aliasing
techniques.)

Color management via ICC profile support (i.e., the
ability to support colors defined using ICC profiles).

Resampling of image data must conform to the requirements
for Conforming High-Quality SVG Viewers as specified in the
description of property 'image-rendering'.

At least double-precision floating point computation on
coordinate system transformation numerical calculations.

A Conforming High-Quality Dynamic SVG Viewer must
support the following additional features:

Progressive rendering and animation effects (i.e., the
start of the document will start appearing and animations
will start running in parallel with downloading the rest of
the document).

Restricted screen updates (i.e., only required areas of
the display are updated in response to redraw events).

Background downloading of images and fonts retrieved from
a Web server, with updating of the display once the downloads
are complete.

If the user agent includes an HTML or XHTML viewing
capability or can apply CSS/XSL styling properties to XML
documents, then a Conforming SVG Viewer must support
resources of MIME type "image/svg+xml" wherever raster image
external resources can be used, such as in the HTML or XHTML
'img' element and in CSS/XSL
properties that can refer to raster image resources (e.g.,
'background-image').